Compact capacitive-inductive impedance unit



" July 22,1969 mrsuo MATSUSHIMA ET AL 3,457,527

COIPACT OAPACTIVE-INDUGITIVE IMPEDANCE UNIT Original Filed April 17, 1962 2 Sheets-Sheet 1 M INVENTORS Ml'rsuo MflTSUSH/ fl July 2 2,, 1969 MITSUQ MATSUSHIMA ETAL 3,457,527

. COMPACT CAPACTIVE-INDUGITIVQ IMPEDANCE UNIT Original Filed April 17. 1962 2 Sheets-Shet 2 T1 4. mfg

United States Patent 3,457,527 COMPACT CAPACITIVE-INDUCTIVE IMPEDANCE UNIT Mitsuo Matsushima and Shigeaki Ogawa, Akita-ken, Japan, assignors to Tokyo Denki Kagaku Kogyo Kabushiki Kaisha, Tokyo, Japan Original application Apr. 17, 1962, Ser. No. 188,173, now Patent No. 3,295,055, dated Dec. 27, 1966. Divided and this application Aug. 22, 1966, Ser. No. 591,048 Claims priority, application Japan, Apr. 20, 1961, 36/ 19,457, 36/ 19,458 Int. Cl. H01h 7/14 US. Cl. 333-79 6 Claims ABSTRACT OF THE DISCLOSURE A compact impedance unit including a tubular body of dielectric material having at least a pair of axially spaced bands of electrically conductive low resistance metal on the outer surface thereof, one of said bands being continued as a layer of electrically conductive low resistance metal on the internal surface of said body to extend in overlapping relation with another of said bands and a winding wound on a ferrite core positioned within said body with its opposite ends each connected to respective bands.

This is a division of application Ser. No. 188,173, filed Apr. 17, 1962, now issued as Patent No. 3,295,055.

This invention relates to a compact impedance unit combining inductance with either resistance or capacitance, all in a simple compact unit.

In one form of the invention, the impedance unit comprises a combination of inductance and resistance, particularly an inductive winding and a Q-damping resistor, the winding being usable as the peaking coil or winding for the wide-band amplification circuit of a television receiving set or the like.

In another form of the invention, the impedance unit comprises an inductive winding and one or more condensers or capacitors. In this form of the invention, the impedance unit is suitable for use as the detecting filter or the like of communication equipment in general, and particularly as the detecting filter or the like of a radio or television set.

Basically, the impedance unit of the invention includes a tubular body of dielectric material, such as porcelain, on which there are at least a pair of axially spaced bands of electrically conductive low resistance metal, these bands being on the external surface of the body and each having a terminal lead electrically connected thereto as by tight wrapping of the lead therearound. A ferrite core is positioned within the tubular body, and preferably is formed with a peripheral recess. A winding is provided on this core, as by being seated in the peripheral recess, and the opposite ends of the winding are electrically connected to respective ones of the metal bands.

In the form of the invention involving an inductance and a resistance, a high resistance material, such as a film of carbon or the like, is provided on the external surface of the body and electrically interconnects the bands. Two bands are used in the event that it is desired to have a parallel connection of the inductance and the resistance and, in such case, one end of the winding is electrically connected to one band and the opposite end of the wind ing is electrically connected to the opposite bands. In the event it is desired to have a series connected inductance and resistance, a third or intermediate band is provided, and one end of the winding is connected to one end band and the other end of the winding is connected to the intermediate band.

Patented July 22, 1969 In the form of the invention involving an inductance and a capacitance, three bands are provided on the exterior surface of the body, and one band is continued as a coating or the like on the internal surface of the body. This forms two condensers having one electrode in common. In this form of the invention, the opposite ends of the winding are preferably connected to those two bands which are applied only to the external surface of the body, and a unit is thus provided in which the winding is connected between two terminals and each condenser is connected between a respective one of such two terminals and the third terminal.

For an understanding of the principles of the invention reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings. In the drawings:

FIG. 1, part A is a side elevational view, partly in axial section, of one form of impedance unit embodying the invention;

FIG. 1, part B is a schematic wiring diagram of the equivalent circuit of the unit shown in FIG. 1A;

FIG. 2, part A is a side elevational view, partly in axial section, of a modification of the unit shown in FIG. 1A;

FIG. 2, part B is a schematic wiring diagram of the equivalent circuit of ithe unit shown in FIG. 2B;

FIG. 3 is a graph illustrating the distributed capacity of the impedance unit embodying the invention;

FIG. 4 is a schematic wiring diagram of the equivalent circuit of the impedance unit shown in FIGS. 5 and 6; and

FIGS. 5 and 6 are axial sectional views through alternative embodiments of the impedance unit as arranged to provide combined inductance and capacitance.

As shown in parts A of FIGURES 1 and 2, metallic electrodes 2' and 2", in the form of bands of silver or the like, are fixed to the outside ends of the tubular cylindrical insulator, or dielectric body, 1. A high electrical resistance material 3, such as a film of carbon or the like, is provided on the external surface of body 1. Leads 4', 4" and 4 are Wound around and secured to the said elec trodes to provide a means of connection.

A combined unit, shown in parts B of each figure, and which consists of a resistor and a winding can be obtained by inserting and securing a ferrite magnetic core 5, which is provided with a winding 6 in a peripheral recess therein, inside the cylindrical insulator 1, and connecting the winding ends or lead wires 7 to the metallic electrodes of silver or the like.

In the event that the impedance unit of the invention is to provide a combination of inductance and resistance connected in parallel with each other, and which is shown in the equivalent circuit of part B of FIGURE 1, the Wind ing lead wires may be connected with the said silver electrodes 2 and 2" as is shown in part A of FIGURE 1. Similarly, in the case that the device of this invention is :to be used as a combination resistance and inductance unit with the resistance and the inductance connected in series, as shown in part B of FIG. 2, this can be effected by applying a third metallic band or electrode 2" of silver or the like, and identical with the electrodes 2' and 2". In this case, one end of the winding, which in the embodiment of FIG. 1 has been connected with the electrode or band 2', is now connected with the electrode or band 2" as shown in part A of FIG. 2. The other coil winding lead -7 re mains connected to electrode 2" which is in turn connected to terminal lead 4", thus providing a series arrangement as shown schematically in FIG. 2B.

It is known to provide peaking coils in which the winding element is connected either in parallel or in series with the resistance element. However, in the present invention the inductive element, comprising the ferrite core 5 and the winding 6, is positioned within the interior of the resistor. Thus, the whole unit is made very compact, in addition to which the inductance unit is protected from damage by external impacts and the like. As the winding is connected to the resistance either in parallel or in series, the number of connected parts can be reduced, thus resulting in an increase in the working efficiency.

Moreover, the ferrite magnetic core, such as used in the present invention, results in the distributed capacity being substantially reduced as compared with that of a conventional air-core Winding. This is graphically illustrated in FIG. 3, in which the upper curve represents the dis tributed capacity of a conventional air-core coil and the lower curve represents the distributed capacity of the inductance unit in accordance with the invention. It is thus seen that for an inductor unit having a given inductance, the distributed capacitance of such inductor unit will be less when the inductor unit is constructed in accordance with'the present invention than a conventional inductor having the same inductance. For example, a conventional inductor having an inductance of 50 microhenriesfwould typically have a distributed capacitance of approximately 3 picofarads whereas an inductor in accordance with the present invention having the same inductance of 50 microhenries would only have a distributed capacitance of ap-.

proximately 2 picofarads. The measurements resulting in the graph of FIG. 3 are based on the following:

Measuring instrument.-Booton Q-meter, type 260-AP Frequency ratio.n=2 Temperature and humidity.20 C., 50%

As shown in FIGURES 5 and 6, the inside and the outside surfaces of the cylindrical porcelain, or tubular 'dielectric body 8, having a high-dielectric constant, are coated with bands of silver or the like to make these bands the internal electrode 9 and the external electrodes 11 respectively, to which the leads are secured by. wrapping therearound. That is, the lead terminals and 10" are securely fixed to the external electrodes 11, and the lead terminal 10" is securely fixed to the internal electrode 9, which is a continuous coating of silver or the like extending to the exterior. Thus two condensers can be obtained as is shown in the equivalent circuit diagram of FIGURE 4.

The magnetic coil core, which is provided with the winding 13 in the peripheral recess at the center of the drum-shaped ferrite magnetic core 12, is then inserted into and securely fixed to the interior of the tubular dielectric body 8 by means of an insulating paint or a binding agent, and thus a'combined unit of the equivalent circuit of the connection can be obtained as shown in FIGURE 4' by connecting the lead wires 14 of the winding with lead terminals 10' and 10" of the abovementioned condenser(s).

The size of the parts is made extremely compact by using the device like this, because the coil core is fixed to the internal space of the said condenser, which is made of one piece porcelain dielectric. For example, in

case of f=100 kc./s., L=45 uh, and C=10 ,uf., the said 7 connected when it is installed into the equipment, thus raising the working elficiency.

Because the coil core is, in addition, inserted into the cylindrical porcelain, troubles of disconnection or shortcircuit or the like due "to external impact are avoided, and because of using ferrite material for the core winding, it has an advantage that the distributed capacity is about 1 pi. smaller than that of a conventional air-core winding.

. What we claim is:

1. A compact impedance unit comprising, in combination, a tubular body of dielectric material; at least a pair of axially spaced bands of electrically -conductive low resistance metal on the outer surface of said body, one of said bands being continued as a layer of electrically conductive low resistance metal on the internal surface of said body to extend in axially overlapping relation with another of said bands; terminal leads each electrically connected to a respective band; a ferrite cone positioned within said body; and a winding on said core having its opposite ends electrically connected to respective bands; said core and said winding forming an inductive impedance component, and said overlapping bands forming a capacitive impedance component.

2. A compact impedance unit comprising, in combina tion, a tubular body of dielectric material; three axially spaced bands of electrically conductive low resistance metal on the outer surface of said body, said three bands including two end bands and an intermediate band; one of said end bands being extended as a layer of electrically conductive low resistance metal on the internal surface of said body and axially overlapping the other two bands to define two capacitive components; three terminal leads each electrically connected to a respective band; a ferrite core positioned within said body; and a winding on said core defining an inductive component and having its opposite ends electrically connected to the other end band and to said intermediate band, whereby said inductive and capacitive components are disposed in a 1r connection.

3. A compact impedance unit, as claimed in claim 1 or 2, in which said ferrite core is formed with a peripheral recess, said winding being positioned within said periph eral recess.

4. A compact impedance unit, as claimed in claim 1 or 2, in which said ferrite core is formed with a peripheral recess, said winding being positioned within said peripheral recess, in which the axis of said core is parallel to the axis of said-body.

5. A compact impedance unit, as claimed in claim 1 or 2, in which the axis of said core is transverse to the axis of said body.

6. A compact impedance unit, as claimed in claim 1 or 2, wherein each of said terminal leads are in the form of lengths of wire wrapped about its respective band.

References Cited UNITED STATES PATENTS 2,759,155 8/1956 Hackenberg 333-79 HERMAN K. SAALBACH, Primary Examiner T. VEZEAU, Assistant Examiner US. Cl. X.R. 317-242 

